Extensible foldable manipulator

ABSTRACT

A MANIPULATOR FOR EXTENDING A TOOL, PERSON OR OTHER LOAD OUT FROM A BASE IN A CONTROLLED DIRECTION AND TO A CONTROLLED EXTENT, COMPRISING ELONGATED SPACERS AND A MULTIPLE-LEVER CONNECTOR, OPPOSITELY HINGEABLE, BETWEEN EACH PAIR OF THE SPACERS. EACH VARYING-ANGLE CONNECTOR HAS A CONTROLLED MOTOR AND AN INTERACTING SYSTEM OF LEVERS, THE OUTERMOT EXTENT OF WHICH FALLS WITHIN A CIRCLE OF APPROXIMATELY THE SAME SIZE AS THE MAXIMUM DIAMETER OF THE SPACERS. OPTIONALLY, THE LEVERS MAY BE OF THE BELLCRANK TYPE OR THEY MAY HAVE SEGMENTAL GEARS AT THEIE ENDS. EACH LINK OF THE MANIPULATOR MAY BE SEPARATELY ANGLED BY ITS CONNECTOR IN EITHER OF TWO OPPOSITE DIRECTIONS AND THEN LOCKED IN ITS ADJUSTED POSITION. IN FOLDING THE MANIPULATOR FOR STORAGE EACH ADJOINING PAIR OF THE LINKS ARE COMPACTLY FOLDED IN OPPOSITE DIRECTIONS.

Oct. 5, 1971 MUELLER ETAL 3,610,058

EXTENS IBLE FOLDABLE MAN IPULATOR Filed July 14, 1969 7 Sheets-Sheet 2FIG. 2

L V i 7 A Omit/MW) IIIHHWJJJJLL IIIIMIIIII FIG. 3

FRITZ K. MUELLER,

ROBERT C. MARTIN,

AND,

J. ROLAND LOYD,

INVENTORSI AT TORNEY.

Oct. 5, 1971 MUELLER ETAL 3,610,058

EXTENSIBLE FOLDABLE MANIPULATOR 7 Sheets-Sheet 5 Filed July 14, 1969 R ED L Y L 0 E L U M .D TA Z N 0 W8 R o CIR IU INVENTORS,

FIG. 5

ATTORNEY Oct. 5, 1971 MUELLER ETAL 3,610,058

EXTENSIBLE FOLDABLE MANIPULATOR Filed July 14, 1969 7 Sheets-Sheet I.

' FRITZ K. MUELLER, ROBERT c. MARTIN,

AND,

J. ROLAND LOYD,

INVENTORS,

ATTORNEY.

INPUT ANGLE Oct. 5, 1971 F. K. MUELLER r-rr AL 3,610,058

EXTENSIBLE FOLDABLE MANIPULATOR Filed July 14 1969 O 20 4O 6O 80 FIG. 9

7 Sheets-Sheet 8 I 0 UT PUT ANGLE I I I I 200 FRITZ K. MUE LLER,

ROBERT C. MARTIN,

AND Jv ROLAND LOYD,

INVENTORE,

ATTORNEY,

Oct. 5, 1971 MUELLER ETAL 3,610,058

EXTENS IBLE FOLDABLE MAN IPULATOR Filed July 14 1969 v 7 Sheets-Sheet 7FRITZ K. MUELLER,

FIG. l2 ROBERT c. MARTIN,

AND J.ROLAND LOYD,

INVENTORS,

BY M M ia p2.

TTORNEY.

United States Patent 01 Patented Oct. 5, 1971 ice 3,610,058 EXTENSIBLEFOLDABLE MANIPULATOR Fritz Kurt Mueller, Robert Cherry Martin, and JohnRoland Loyd Ill, Huntsville, Ala, assignors to Astra-Space Laboratories,Inc., Huntsville, Ala.

Filed July 14, 1969, Ser. No. 841,324 Int. Cl. F16h 27/02; B0511 US. Cl.74--89.17 8 Claims ABSTRACT OF THE DISCLOSURE A manipulator forextending a tool, person or other load out from a base in a controlleddirection and to a controlled extent, comprising elongated spacers and amultiple-lever connector, oppositely hingeable, between each pair of thespacers. Each varying-angle connector has a controlled motor and aninteracting system of levers, the outermost extent of which falls withina circle of approximately the same size as the maximum diameter of thespacers. Optionally, the levers may be of the bellcrank type or they mayhave segmental gears at their ends. Each link of the manipulator may beseparately angled by its connector in either of two opposite directionsand then locked in its adjusted position. In folding the manipulator forstorage each adjoining pair of the links are compactly folded inopposite directions.

In maneuvers outside or on the interior of space vehicles or submarinesand in rescue of persons from upper floors of buildings on fire and fromother high places such as mountain peaks and damaged towers, there is aneed for an efiicient extensible carrier or manipulator, controllablefrom its base or tip, having straight spacers with jointed connectorsthat may be controllably operated either to extend the spacers into avariety of manipulator shapes and positions, or to fold them into acompact mass on or near the vehicle or other base. The most compact massof their folded position and the largest variety of their extendedpositions in a plane are achieved when the connecting means between eachpair of the straight spacers permits the pair to be folded from a fullyextended, straight-line position thru various angles up to 180 degrees,in each of two opposite directions, and also permits separatemotor-control of each connector so that its pair of spacers may beextended or folded thru angles that vary from the angles between otherpairs of spacers. With such [flexibility of the connectors: (1) thespacers may be folded in the manner of compacting the sections of acommon carpenters rule, with one pair of the spacers folded in onedirection against each other and the next spacer of the series to befolded against that pair in the opposite direction; and (2) a supportfor a tool, person or other load at the outer tip of the connectedspacers may be moved to any desired position.

'In view of these facts, an object of this invention is to provide anextensible and foldable manipulator having: a plurality of elongatedspacers; a connector between each pair of spacers comprising a pluralityof pivoted levers (optionally having geared ends) that are hinged forangular motion in each of two opposite directions; a motor; means,connecting the motor and an adjacent pivoted lever and connecting thesaid adjacent lever to other levers, for adding the angles of motion ofthe several members into the angle of movement between the pair ofspacers; and means for separately controlling and locking the motors.

Another purpose is to devise a mechanical movement having a pair ofhinged elements, and a connector between them that comprises: a motor onone of the said elements and means to control said motor; a linearlyarranged series of pivoted members between the elements, each pair ofthese members being mounted for pivoted movement in each of two oppositedirections; means connecting the motor and an adjacent pivoted memberfor hinging the adjacent member thru a predetermined angle; meansconnecting the said adjacent member to a second pivoted member of theseries for hinging it thru a pre determined angle; means connecting thesaid second memher to a third member of the series for pivoting it thrua predetermined angle that is equal to the sum of the first-mentionedangles; and means connecting the said third member to a second one ofthe said pair of hinged elements, for pivoting it thru a predeterminedangle that is equal to the sum of all said predetermined angles.Optionally, there may be any number of the said pivoted members as partsof the connector between thepair of hinged elements.

A further objective of the invention is to provide such a mechanicalmovement having the said pair of hinged elements and also having atleast one other, a third, hinged element, connected to the said secondhinged element by a second series of the pivoted members; whereby thesecond hinged element may be compactly folded against the first one inone direction and the third hinged element may be compactly foldedagainst the second element in the opposite direction.

These and other objectives of the invention will become more fullyapparent from the following detailed description and the accompanyingdrawings.

FIG. 1 is a side view, partly broken away and in section from a planethru the axis of hinged spacers, showing a pair of the spacers as havingbeen compactly folded against each other by the motor and the gearedlevers of the connectors that are between the spacers.

FIG. 2 is a side view, partly broken away, of a pair of the spacers,connected by geared levers with the axes of the spacers in a straightline; in this figure the tubular spacers and the bellows 30 are shown ascut in halves along a vertical plane to expose the connector levers inelevation.

FIG. 3 is a bottom view from the plane 3-3 of FIG. 2, partly broken awayand with the bellows removed, of the spacers and pivoted connectingmembers of FIG. 2.

FIG. 4 is a side view, partly in section and partly broken away, of aplurality of spacers and pivoted spacer connecting members that comprisebellcrank levers, with the second spacer of the set shown as having beenangled clockwise degrees by motor and bellcrank levers from its positionin alignment with the base spacer 50, and with the third spacer shown ashaving been folded 180 degrees in the opposite, counterclockwisedirection.

FIG. 5 is a top plan view, partly broken away, showing a pair of spacerswith their axes in a straight line, hinged by the bellcrank-lever typeof connectors.

FIG. 6 is a side view of the bellcrank-lever form of link shown in FIG.5, showing a pair of spacers as having aligned axes.

FIG. 7 is a side view of the link, with the bellows in place, showingthe right-hand spacer to have been moved by the link motor 30 degrees ina clockwise direction from its position in FIG. 6. In this figure thebellows and one of the spacers are shown as cut in halves along avertical plane.

FIG. 8 is a side view of the link, with sectioning similar to that ofFIG. 6, showing the right-hand spacer as moved 60 degrees in acounter-clockwise direction from its position in FIG. 6.

FIG. 9 is a graph showing curves for the clockwise and counter-clockwisemovement of the spacers in a link having the bellcrank-lever type ofconnector.

FIG. 10 is a block diagram, indicating the electrical control system ofthe invention.

FIG. 11 is a block diagram, indicating the link-motor control panel.

FIG. 12 is a side view of the invention shown as in a firefightingapparatus in use at a fire, with parts of a building and truck shown asbroken away.

Hereafter in this spacification the term link is used to refer to thecombination of connected parts of two of the tubular spacers of themanipulator and a connector, comprising levers, between the spacers.

Basically, the manipulator comprises: a plurality of movable connectedpairs of spacers; a connector having at least three angularly movableelements (shown as gears in FIGS. 1 to 3, and as levers in FIGS. 4 to8); a linkdriving, reversible motor (shown at 1 in FIG. 1 and at 32 inFIG. 4); a link-holding brake, shown as electro-magnetic in FIG. 4 at34; a relatively fixed support at a base of operationsfor example, thewall 3 of FIG. 4; means for attaching the innermost or base link to therelatively fixed support (which may provide controllable angular motionand locking of the base spacer at the support or it may be a stationaryfastening means, for example, the bolts of FIG. 4); and a power supplyand control means, as indicated in FIG. 10.

In FIGS. 1 to 3, the controllable motor 1, turns the elongated nut 4(fixed to a shaft, 5, shown in FIG. 1) which helically reciprocates onthe screw 6 and thus advances or retracts the rack 7. This rack isfastened to the screw by the pin 8, and moves between the closelyfitting sides of a groove in the slide bearing 9.

The rack rotates the pinion 10 which is mounted on axle 11, and thispinion turns the gear segment 12A. This segment is at one end of thedouble-geared lever 12; and at its other end the gear segment 12B islocated. This segment 12B, together with the central part 12C, rotatesabout the axle 14, which, like the motor 1, is fixed to the tubularspacer 16. Also fixed to the spacer there is a segmental gear, 18, thatmeshes with the gear segment A of the single-geared lever 20.

The floating axle 22 pivots with the lever 12 about the fixed axle 14and forces the gear 20A (mounted on the floating axle) to rotateclockwise (as shown in FIG. 1) about the fixed gear 18. The lever 20forces the axle 24 to pivot about the axle 22; and on this axle thesegmental gear 26 is rotated. Since it is fixed to the second tubularspacer 28 of the link and is in mesh with the gear segment 12B, itpivots the spacer 28 about the axle 24, which is fixed to this spacer.

This multiple-lever type of connector between the spacers permits aplurality of the manipulator links to be compactly folded, thru 180degrees, alternately in opposite directions, as indicated in FIG. 4.This folding is possible because of the structure of the linkage,eliminating jamming together of the spacer ends before they are foldedthru the desired 180-degree angle. This invented structure also permitsuse of a foldable bellows that has a cross-sectional circle ofapproximately the maximum diameter of the spacers. The length of eachpair of spacers is determined by the specific use of the manipulator andthe power of the link motor between the spacers. All of the variousspacers may have the same length; or they may have varying lengths.Their lengths and numbers are de termined by the maximum desired reachof the outer tip of the manipulator.

For clarity and convenience of illustration no bellows is shown in FIGS.1, 3 to 6, and 8. But optionally and preferably a waterproof bellows ofthe type shown at 30 in FIGS. 2 and 7 is used to flexibly protect eachof the illustrated connectors. In some specific uses-for example inspace or under watersuch a bellows is especially desirable. It may bemade of stainless steel, Phosphor bronze or other resilient metal,rubber or other resilient plastic, or fabric that is impregnated andcoated with resilient plastic.

A bellows having a maximum diameter that is only slightly larger thanthat of the tubular spacers is used. This small diameter, permitting thedesired compact folding of the manipulator when it is storedfor examplein a small auxiliary housing or other space adjacent to the wall of avehicle, is made possible by the fact that the levers of the inventedconnector are sufficiently short and numerous for their ends, in all thepivotal positions of the levers, to lie within a circle that has adiameter equal to or only slightly exceeding that of the tubularspacers. When this circle of the levers ends slightly exceeds that ofthe spacers, small metallic shoes optionally may be placed on each ofthe lever ends that lie within the bellows-in positions that preventhanging of the bellows on the segmental gears.

Optionally also-and especially for underwater usethe bellows may befilled with compressed air.

An alternative and currently preferred form of the connector betweenspacers, shown in FIGS. 4 to 8, has bellcrank levers instead of thegeared levers of FIGS. 1 to 3. Three connectors of this bellcrank-levertype are illustrated in FIG. 4 as connecting tubular spacers that havebeen compactly folded, alternately in opposite directions, 180 degreesfrom their position in which the axes of the spacers are in a straightline.

In this figure, the reversible motor 32, the reduction gear 33 and thecontrollable magnetic brake 34 (which holds the link in any adjustedposition) are similar to the motor, gear and brake of the structureindicated in FIGS. 1 to 3. The motor 32 rotates the screwthreaded shaft36; and this screw reciprocates the nut 38. In the compactly foldedposition of the manipulator as shown in FIG. 4 this nut has reached theright-hand limit of its travel; and since the push-pull bars 40 arepivoted on the nut at 42 and on the bellcrank lever 44 at 46, the nuthas forced lever 44 to the limit of its clockwise pivoting about itspivot bearing. This bearing has an axle 48 that is fixed at each end tothe tubular spacer 50.

The lever 44 comprises a pair of spaced, parallel, similarly shapedelements that are held properly spaced apart *by the axle 46 and bars40. Each of these elements comprises: a central portion 44A; amotorward, bellcrank portion 44B; and a second bellcrank portion 44C.

FIG. 6 shows two of the spacers, 50 and 52, and a connector betweenthem, in position in which the axes of the spacers are in a straightline; and FIG. 7 shows the same set of spacers and connector with spacer52 having angularly moved in clockwise direction 30 degrees from itsposition of FIG. 6. In this motion the plane containing the axes of 46and 48 has moved thru 4.6 degrees from its vertical position, shown inFIG. 6, to its position in FIG. 7. As shown in FIG. 7, this pivotalangle has been amplified into the angle of 30 degrees between the axesof the spacers. This amplification is made possible, within the desiredsmall compass of the spacers, by the invented bellcrank-lever system.

As the bellcrank lever 44 pivots clockwise it moves the axle 54downward, together with a portion of the bellcrank lever 56. This leveris forced to pivot on the axle 54 because its left-hand bellcrank arm56A is pivoted with respect to the push-pull bar 58, and this bar ispivoted on the fixed axis at 60 with respect to the spacer 50.

The bellcrank lever 56 has a middle part 56B, having a lever arm of axisextending between axle 54 and an axle, 62, that is connected to lever56. In its pivoting, this line between 54 and 62 moves thru a greaterangle with respect to the original horizontal plane containing thealigned axes of spacers 50 and 52 (as shown in FIG. 6) than the anglemoved by the line between axles 48 and 54 with respect to the saidoriginal horizontal plane. This amplification of angle is due to thefollowing functions of an interacting system of the levers, axles andpushpull bars: the axle 54, as shown in FIGS. 6 and 7, is forced bylever 44 to move clockwise and to the left in reaching its lowerposition. This leftward motion causes the angle between the axes ofelements 56A and 58 in FIG. 7 to be less than it was in FIG. 6. Inconsequence, the axle 64 is moved clockwise and the axis line hetweenaxles 54 and 62 is moved clockwise, increasing its angle with thehorizontal plane. This amplification of angle is in addition to theincrease in this angle that is due to the pivoting of the lever 44 about48.

The axle 62 is the fulcrum of a third bellcrank lever, 66. In FIG. 7this fulcrum has moved clockwise and downward a greater distance fromits position in FIG. 6 than the distance thru which axle 54 has movedfrom its position in FIG. 6. This amplification of distance is due tothe difference in the lengths of the arms of lever 56. Because of thislowering or advancement of axle 62 the line between it and the axle 65on the third bellcrank lever 66 (also pivoting clockwise about itsaxison axle 62) begins its pivotal movement at a considerably lower orfurther advanced position than the axle 54.

Due to the fact that the angle between the line 54-62 and the horizontalplane is greater than that between 48-54 and the horizontal and thefurther fact that the axle 68 is res-trained by its attachment to lever44 at 70, the angle between the line 62-65 and the horizontal is stillgreater than the similar angle made by the line 54-62.

In like manner, the angle made with the horizontal by the axis of thetubular spacer 52 is amplified with respect to the angle made by theline 62-65. This output angle of the second spacer 52 is shown asdegrees in FIG. 7, whereas the input angle between the line 46-48 and avertical plane in a preferred engineering design is only 4.6 degrees.

Similar progressive increases of angular movement in the geared-leverstructure of FIGS. 1 to 3 are also made; but in this form of theinvention each of these increases is the same as every other. Whereas,in the preferred, bellcranklever invention form of FIGS. 4 to 8, theprogressive increases are not exactly equal. In the preferred design ofthis form three bellcrank levers are used in the connector and theirlengths are such that the said increases in angle occur according to thegraph of FIG. 9.

An important result of the invention is the operators ability to pivot aselected link in either clockwise or counterclockwise direction thru anyangle (up to the 180- degree angle used in folding the manipulator), andto hold that link in its adjusted position. This pivoting in either oftwo opposite directions is achieved with either the geared-lever or thebellcrank-lever inventive form. In the bellcrank-lever form theincreases of angle in the steps of the angle-adjusting motions of theconnector are the same in either clockwise or counterclockwisedirection, but in the preferred, bellcrank-lever form there is a smalldifference in the above-described amplification of angles in the twoopposite directions. This difference is indicated in the curves of thegraph of FIG. 9.

According to this graph, and as indicated in FIG. 8, in the preferreddesign a counterclockwise input angle of 10.3 degrees achieves aresultant counterclockwise output angle of degrees between the axes ofthe two connected spacers. The principles involved in the motions of theconnector parts of FIG. 8 are the same as those described above inconnection with FIG. 7.

After a link has been moved into its desired angular position thereversible motor is stopped and the link is locked in position by theautomatic or operator-controlled magnetic brake 34. In the usualoperation of the manipulator the angles of the lower links are firstadjusted to provide for its extension out from its base until its tip(carrying a tool, a hose, a housing, a person or the like) is near itsdesired final location, and then the tip link (or pair of outer links)is actuated until the tip is in its proper position.

After a particular operation is finished the manipulator is folded inthe manner indicated in FIG. 1 or FIG. 4. In FIG. 4, the base spacer 50of the manipulator is shown as fixed to the wall 3, but (as indicated inFIG. 12), it optionally may be pivotally and lockably mounted on thewall. This element 3 optionally may be an outer wall of a vehicle, ahousing on a vehicle, or a platform. In folding the manipulator againstelement 3: the tubular spacer 52 has been folded degrees in onedirection; the tubular spacer 74 has been folded 180 degrees in theopposite direction; and a fourth spacer (not shown) has been folded (byits connector which is shown as partly broken away) 180 degrees in thesame direction as was the spacer 52.

This folding operation may be begun at or near the tip of themanipulator or at its base. If a person or spillable liquid or anunfastened device is supported by the tip the tip link is preferably thelast to be folded.

ELECTRICAL CONTROL SYSTEM Base-power console The base-power console,located at the support of the manipulator, is shown schematically at 76in FIG. 10. It is on the vehicle or other base of operations, providesfor the input power connection, which, for example, may be of 28 voltsDC. It also contains the on-off power switch, circuitry for protectionagainst overloads and short circuits, the voltage amplifier for theactuator motors, and a power supply for the operators proportionalcontrol of the voltage amplifier input. This console is connected to thebase of the manipulator by an electrical cable.

Link motive power Basically, the motive power of the connector betweeneach pair of the spacers comprises a driving motor and a locking brake;and optionally it may also comprise the switches to limit the motion ofmechanical parts of the connector by control of the motor.

The driving motor, energized by current from the amplifier in the baseconsole, is under the command of an operator who optionally may be atthe console, or the base-attachment link, or outer, tip link. This motoris preferably a DC. torquer, which exhibits linear speedtorquecharacteristics, provides torque at low speeds, and can be indefinitelystalled without damage.

The brake for each of the connectors iselectromagnetic. It is on thesame shaft as the motor and is used to lock a link of the manipulatorwhen angular motion of this particular link is not desired. It thusholds the link so that its pair of spacers are at any angle desired bythe operator. The other link-angle controls-namely, the optionalmechanical stop and the limit switches-limit extreme travel of theconnector. Preferably the brake is automatically actuated when the motoris stopped.

OPERATOR-CONTROL CONSOLE The operator-control console, which is in aseparate box, may be plugged in and mechanically mounted at either endof the manipulator, or it may be attached to some suitable holder on theoperator, such as a belt or bracket.

As indicated in detail in FIG. 11, the console has a control switch oneach link; it allows the operator to select the link to be operated andthe direction of its angular motion. The switch lever for a particularlinkfor example, 78, may be pivoted up, toward the plus sign, to providemotion of the outer spacer of the link in one direction, or down, towardthe minus sign, to provide motion of this spacer in the oppositedirection. At about the same time the operator controls the speed of thelink motor by the potentiometer 80. This potentiometer determines theoutput voltage of the amplifier.

The operator-control box is sealed, for protection of the controls inunderwater use or in rain, and all the controls are waterproofed bymeans of rubber boots, and are adapted for operation by an astronautwith space-suit gloves or a diver with diving-suit gloves. Optionally, acable of any chosen length may be provided for connecting the box to theactuator.

The invented, compactly foldable and variously extendable device may beused in various applications-for example on space vehicles, satellites,submarines, and in firefighting. One example of these uses is shown inFIG. 12 as on a fire truck at a building of which an upper story is onfire. The motors of the connectors between spacers of the manipulatorhave been controllably actuated and locked until the tip spacer 82 isadjacent to the upper room in which the fire is located, with its point84 close to the window, the frame of which is indicated at 86. The motorof the tip link then has been actuated to force the steel tip thru thewindow-breaking it if not openuntil, as indicated in FIG. 12, the pointis sufficiently far in the room to spray and fill it withfireextinguishing chemicals. This spraying is controllably done by apump on the truck, sending the chemicals thru the hose 88. This hose isattached to the sides of each spacer by the bands or loops 90; and atthe hole 92 in the tip spacer the hose enters the hollow interior of thespacer, and so is flow-connected with the hollow, fluid-supplying point84. After the firefighting operation is complete the manipulator iscompactly and efiiciently folded, by means of the motors and theinvented system of connector levers, on or into the rear part of thetruck body.

Without departing from the principles of the invention various changesin the specific disclosed structures may be made. For example, in thestraight-line position of the spacers shown in FIG. 6 all the axes ofthe axles 48, 54, 62 and '65 may be exactly aligned with the coincidingaxes of the spacers 50 and 52, in the manner of the lever fulcrums inFIG. 2.

We claim:

1. An extensible, foldable device having at least one pair of spacersand connecting means between the spacers for controllably angling themin either of two opposite angular directions, said connecting meanscomprising:

a lever, 'mounted for pivotal movement on an end portion of a basespacer of said pair, having: a fulcrum at the axis of said pivotalmovement; a connection, adjacent to said base spacer and spaced fromsaid fulcrum, for application of turning force on one end portion of thelever in either of two opposite angular directions; and an axle atanother portion of the lever, spaced farther from said fulcrum than saidconnection, for transmittal of force to a second lever;

a second lever, mounted for pivotal motion on the said axle andreceiving force thru said axle, one of its end parts having a secondfulcrum and means pivotally connecting this second fulcrum to said basespacer, and another of its parts having a second axle, spaced fartherfrom the second fulcrum than said first-named axle, for transmittal offorce to a third lever;

a third lever, pivotally mounted on the said second axle, one of its endportions having a third fulcrum and means pivotally connecting the thirdfulcrum to the said first-named lever, said third lever having means atanother end portion, connected to a second one of said pair of spacers,for angling the said second spacer; and

means, connected to the said base spacer and to the said connection, forcontrollably pivoting said firstnamed lever and holding it in anadjusted position;

the said interacting levers being constructed and arranged to adjust andhold the said second spacer at an angle that is considerably greaterthan the adjusted angle between said first lever and the axis of saidbase spacer. 2. A device as set forth in claim 1, in which the lengthsof said levers are such that all of their parts, in all of their angularpositions, are within circles, each of which has an area approximatelyequal to the maximum crosssectional area within peripheries of saidspacers; and in which the device comprises a bellows around said levers,sealably connected at each of its ends to adjacent ends of the pair ofspacers.

3. A device as set forth in claim 1, in which said second and thirdfulcrums comprise portions of segmental gears, and in which the saidconnectionand two connecting means comprise gear portions.

4. A device as set forth in claim 1, in which said levers, axles,connection and connecting means are constructed and arranged to permitfolding of said second spacer, in either of said two angular directions,with its axis pivoting thru 180 degrees with respect to the axis of saidbase spacer.

5. A device as set forth in claim 1, in which: said means forcontrollably pivoting said first-named lever is a motor; said levers arebellcrank levers; said connection comprises a bellcrank arm of saidfirst-named lever, a push-pull bar, a pintle between said push-pull barand said bellcrank arm, and means connecting said push-pull bar to saidmotor; and each of said connecting means comprises a push-pull bar andmeans pivoting it to a lever.

6. A device as set forth in claim 5, in which the lengths of said leversare such that all of their parts, in all of their angular positions arewithin circles, each of which has an area approximately equal to themaximum crosssectional area within peripheries of said spacers; and inwhich the device comprises a bellows, around the said levers, sealablyconnected at each of its ends to adjacent ends of the pair of spacers.

7. A device as set forth in claim 6, in which the ends of said leversthat are adjacent to the inner surface corrugations of the said bellowsare rounded.

8. A device as set forth in claim 4, having at least three of saidspacers, in which the said second spacer is foldable in one angulardirection with its axis at 180 degrees to the axis of said base spacer,and in which a third spacer is foldable in the opposite angulardirection, with its axis at 180 degrees from the axis of said secondspacer.

References Cited UNITED STATES PATENTS 617,884 l/l899 Poe 7489.17681,890 9/1901 Snow 137-615 2,390,029 11/1945 Parsons 74-8917 3,199,5538/1965 Garrett et al l41-388 3,228,421 1/1966 Sheiry 137-35516 3,266,0598/1966 Stelle 285223 3,399,909 9/1968 Ambrose l37-615 2,414,774 1/ 1947Spinks 248277 3,470,981 10/ 1969 Huxley III 248277 WILLIAM F. ODEA,Primary Examiner W. S. RATLIFF, JR., Assistant Examiner U.S. Cl. X.R.

